Gas Optimizations

[code423n4]

[G-01] - Use custom errors rather than revert()/require() strings
Custom errors are ABI encoded. Consequently, they can be decoded using ABI decoders. This makes it more gas efficient than « revert string ».

File : puttyV2.sol -
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puttyV2.sol:598
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puttyV2.sol:765

File: puttyV2Nft.sol -
puttyV2Nft.sol:12
puttyV2Nft.sol:13
puttyV2Nft.sol:26
puttyV2Nft.sol:27
puttyV2Nft.sol:28
puttyV2Nft.sol:41

[G-02] - Duplicated Require()/Revert() checks should be refactored to a modifier or function
This would reduce the deployment costs.

File: puttyV2.sol -

1. Not owner requirement :
   puttyV2.sol:395
   puttyV2.sol:475
2. Incorrect ETH amount requirement :
   puttyV2.sol:329
   puttyV2.sol:353
   puttyV2.sol:429

[G-03] - Expressions for constant values such as a call to KECCAK256() should use immutable rather than constant
A constant declared as KECCAK256() is re-calculated each time it is in use.

File: puttyV2.sol -
puttyV2.sol:89
puttyV2.sol:95
puttyV2.sol:101

[G04] - Using >0 costs more gas than != 0 when used on a uint in a require() statement.

File: puttyV2.sol -
puttyV2.sol:598
puttyV2.sol:599
puttyV2.sol:611

[G05] - It costs more gas to initialize variables to zero than to let the default of zero be applied.

File: puttyV2.sol -
puttyV2.sol:556
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puttyV2.sol:624
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puttyV2.sol:658
puttyV2.sol:670
puttyV2.sol:728
puttyV2.sol:742

[G06] - Pre-increments (++i) cost less gas than post-increment (i++), especially inside for loops.

File: puttyV2.sol -
puttyV2.sol:556
puttyV2.sol:594
puttyV2.sol:611
puttyV2.sol:624
puttyV2.sol:637
puttyV2.sol:647
puttyV2.sol:658
puttyV2.sol:670
puttyV2.sol:728
puttyV2.sol:742

[G07] ++i should be unchecked{++I} when it is not possible for them to overflow (ie. In a for loop).

File: puttyV2.sol -
puttyV2.sol:556
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puttyV2.sol:624
puttyV2.sol:637
puttyV2.sol:647
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puttyV2.sol:728
puttyV2.sol:742

[G08] Using private rather than public for constants saves gas.

File: puttyV2.sol -
puttyV2.sol:89
puttyV2.sol:95
puttyV2.sol:101

[G09] External functions are less expensive than public
All the functions (except those related to « transfer ») are set to public. Consider turning those that are only called outside the contract as « external » to save gas.